AMHERST - A 20-year-old University of Massachusetts student, who struck his head on the sidewalk after being punched by a 19-year-old Amherst man early Friday, is in serious but stable condition at Baystate Medical Center in Springfield.

Police, summoned to North Pleasant Street and Kellogg Avenue shortly after midnight for a reported assault, found the victim unresponsive and suffering from head trauma, according to a release issued by Amherst police.

Police determined the assailant to be James A. Harris, 19, of 116 Pomeroy Lane. Harris fled the scene and was found hiding in an apartment on Kellogg Avenue. Harris is not a UMass student, police said.

Harris was charged with assault and battery/serious bodily injury, police said. He is slated to be arraigned in Eastern Hampshire District Court in Belchertown.

Police said the assault occurred after the two men exchanged words on the street. Harris struck the victim in the face.